温度作用对孔隙岩石介质力学性能的影响

Mechanical properties of porous rock media subjected to temperature effect

利用模型材料制作了孔隙岩石物理模型,利用CT扫描和统计学原理获得了物理模型内部孔隙数量、孔隙空间位置和孔隙间距等分布特征,通过不同孔隙率物理模型温度作用下的单轴压缩试验,分析了温度作用后孔隙物理模型的抗压强度、弹性模量和泊松比等力学参数与温度和孔隙率之间的关系,运用CT扫描试验探讨了温度作用下孔隙微观结构的演化规律。研究发现:孔隙物理模型与天然孔隙岩石相比具有较好的几何相似性和一致的孔隙结构分布特征;随着作用温度点的升高,同一孔隙率的物理模型的抗压强度基本呈上升趋势,孔隙率的增大减弱了温度对物理模型抗压强度的影响作用;在相同温度条件下,随着孔隙率的增加,物理模型的抗压强度呈下降趋势。随着作用温度点的升高,同一孔隙率的物理模型的弹性模量基本都呈下降趋势;随着温度的升高孔隙率对泊松比的影响逐渐减弱;温度引起物理模型内部孔隙几何形态和孔隙数量的改变是引起宏观力学参数发生变化的主要内因。150℃似乎可以作为温度对孔隙物理模型力学参数影响的一个门槛值。研究成果揭示了温度对岩石宏观力学性能及微观孔隙结构演化规律的影响机理。

The modeling materials are employed to fabricate porous physical models for rock based on the statistical distribution features of pores in natural rock. A series of uniaxial compressive tests on the physical models with varied porosities are carried out under temperature effect. The influences of pores and temperature on the mechanical properties of porous physical models are investigated, including compressive strength, elastic modulus and Poisson＇s ratio. The evolution law of microscopic porous structure subjected to temperature effect is probed using the CT scanning technique. The results indicate that with the increase of temperature, the compressive strengths of physical models with the same porosity basically rise. The bigger porosity weakens the effect of temperature on the compressive strength. The elastic moduli of physical models with the same porosity present a declining trend with rising temperature. The influence of pores on Poisson＇s ratio becomes inconspicuous with the temperature rise. The temperature-induced changes of geometric form and quantity of pores in physical models are the main intrinsic factors which lead to the diverse macroscopic mechanical properties of physical models. The temperature of 150~C seems to be the threshold temperature which induces different mechanical properties of the porous physical models. The research reveals the effect mechanism of temperature on the macroscopic mechanical properties and microscopic evolution of porous structure of the physical models.